java.lang.IllegalStateException: Mailbox is in state CLOSED, but is required to be in state OPEN for put operations

[zh...@greatld.com]

程序时常会报：java.lang.IllegalStateException: Mailbox is in state CLOSED, but is 
required to be in state OPEN for put operations。 请问原因是什么？以及如何避免。
zh...@greatld.com